Spit up

Soo my son literally pukes alllllll the time. He's not upset about it though. He will smile real big open his mouth and it will just roll out.. then he laughs lol I asked my Dr. Awhile ago and she isn't too concerned because he's gaining weight (90th percentile for both height and weight) and he has PLENTY of wet diapers... I just don't know what to do... even though my Dr says it's fine it bothers me. I figure if he had reflux or lactose intolerance he would be crying about it? He is formula fed and I only let him eat 4.5- 5 Oz at a time even though he gets sooo mad at me when I take it away. I just don't know what else to do. Any suggestions? Any other momma going through this?

Also he doesn't seem to do it when I put him down to sleep. I will give him a bottle burp him then put him in his bassinet or crib (crib for naps time bassinet for night time) he sleeps on his back over night and his tummy for nap time.